That ethanol (ETOH) has effects on the male reproductive axis is well known. While it has been noted that ETOH significantly reduces testosterone levels through direct action at the level of testicle, it is clear that indirect central effects on the thalamic-pituitary axis also exist. The exact locus of these effects remain largely unknown, although the hypothalamus has been largely implicated. It is the intent of this proposal to further investigate both the exact locus and nature of central and peripheral effects of ETOH by experiments aimed at obtaining more direct data than has previously been done. The direct consequences of chronic ETOH administration on hypothalamic gonadotropin-releasing hormone (GnRH) and beta-endorphin content and concentration will be studied. Release of GnRH and beta-endorphin into the portal blood system will also be assessed by the technique of portal vessel catherization. Thus, the content of GnRH and beta-endorphin can be correlated with release into portal blood and with peripheral serum luteinizing hormone (LH) levels. The bioactivity of GnRH in the presence of ETOH will be studied utilizing the pituitary cell culture method and measuring LH release. Finally, the physiochemical nature of GnRH will be examined by isoelectric focusing. To investigate the direct toxic effect of ethanol at the pituitary level total pituitary LH content, bioactivity and secretion will be studied in the ETOH-fed animal, and compared with that of isocalorically pair-fed controls. Content will be assessed by radioimmunoassay (RIA); bioactivity by rat interstitial cell testosterone assay, a well characterized in vitro bioassay. Isoelectric focusing will be employed to determine any change in the isohormone pattern induced by ETOH. The direct in vitro effects of ethanol on LH will be studied using the pituitary cell culture model; in this manner ethanol can be directly applied to normal pituitary cells and subsequent LH secretion determined. Lastly, the effects of ethanol on the testicle will be studied in a novel manner by assessing the effects of chronic feeding on beta-endorphin content and concentration in the gonad. There is recent data to suggest that beta-endorphin localized in testicular Leydig cells plays an important role in modulating reproduction yet the effects of ETOH on this peptide have not been studied. The proposed project will take approximately 3 years to complete. The results should be most enlightening in determining the specific areas and mode of ethanol action on the reproductive axis.